[docs] Fix Sketch link

Author: mbrookes

docs/src/pages/discover-more/related-projects/related-projects.md

@@ -8,7 +8,7 @@ Feel free to submit a pull request to add another project; it will be accepted i
 
 ## Design resources
 
-- **Sketch**: [Sketch for Material-UI](https://material-ui.com/store/item/sketch-react/) — A large UI kit with over 1,500 handcrafted Material-UI's symbols 💎.
+- **Sketch**: [Sketch for Material-UI](https://material-ui.com/store/items/sketch-react/) — A large UI kit with over 1,500 handcrafted Material-UI's symbols 💎.
 - **Figma**:
   - https://material.5ly.co/ for Material-UI made by Fively Team.
   - https://ui-kit.co/ a starter kit for your Material Design 2 project.